Treating stenosis of a bodily conduit by means of a radially expandable tubular implant with a cutout or meshed structure, currently called a “stent”, is well known. This device is introduced in the unexpanded state into the conduit to be treated up to the area of the stenosis, and is then expanded, particularly by means of an inflatable balloon, or, when it has an self-expandable structure, is released by a sheath that contains it in its contracted state.
In particular, the use of one or two stents to treat a bifurcation is known. In the simplest case, a single stent is implanted through the bifurcation (method called “provisional stenting”). In more complex cases, two tubular, stents are positioned according to various methods (called “T-stenting, “culotte,” “crush,” etc.). These methods, that aim to hold two tubes in the bifurcation, have the disadvantages of involving either a very significant metallic bulk, or a partial and incomplete support of the arterial wall in the “carena,” that is, the area where the secondary conduits are connected to each other. Consequently, and in all scenarios, simple tubular stents do not provide good clinical results even if they are coated with an active molecule; in fact, stenosis of the conduits of the bifurcation tends to reappear after several months (restenosis), which involves a new intervention.
It is to be noted that in order to improve blood flow in the secondary duct that is partially obstructed by the stent, the practitioner may introduce a balloon through a mesh of the stent in order to enlarge this mesh. This enlargement is limited by the perimeter of the mesh, which has a smaller diameter than the arterial section in the bifurcation, and therefore does not allow a sufficient opening to be offered.
EP 1,034,751 A2 discloses a balloon expandable stent capable of reducing the degree of inhibition of a blood stream to a branched blood vessel. In the stent, connection portions between adjacent wavy annular members are weaker than other parts and can be broken. In use, the stent may be placed in a blood vessel passing a side branch, and dilated. A balloon may then be inserted through the side wall of the already-dilated stent at the opening to the side branch and inflated, as shown in FIG. 18. As a result, while the stent dilation does not change, connection portions adjacent the balloon are broken to form a hole in the stent side wall almost equal to the inflated diameter of the balloon. Because of the plastic nature of the stent material, the hole remains open, facilitating flow through the side branch. This stent is intended to be used in T-bifurcations, i.e. where the main conduit is straight and the side branch has a much smaller diameter than the main the conduit.
Stents called “dedicated” stents for treating a bifurcation are known from, for example, documents WO 2005/094728, WO 01/074273 or U.S. Pat. No. 6,210,429. In general they have a special feature of having an opening in a portion of the stent in order to allow communication with the secondary conduit without disturbing the blood flow. However, this previously made, single opening necessitates that the stent be placed very precisely longitudinally and angularly in the bifurcation. Different means are provided to facilitate this placement, such as a second guide or a second balloon, but their utilization makes the implantation procedure complex and long, and the placement remains especially uncertain.
Providing a stent in at least two partially separated parts, wherein one, in a truncated form, is designed to be placed in the main conduit, and wherein at least one other, in a cylindrical form, is designed to be placed in a secondary conduit, is known from documents EP 0,909,147 or WO 2004/017865.
However, treatment of a bifurcation with such stents remains a relatively long operation that is difficult and delicate to carry out, particularly considering the necessary precise position of the stent in the bifurcation.
Documents U.S. Pat. No. 6,258,117 or EP 1,290,987 describe stents comprising a plurality of connection structures delimiting portions of the stent between them, these connection structures allow different portions of the stent to be separated after implantation. Said stent portions, therefore released from each other after implantation, allow a better adaptation of the stent to the shape of the bodily conduit treated.
These stents are not adapted to the treatment of a bifurcation and do not solve the aforementioned disadvantage connected to such treatment.